diff --git a/flight/Flight.php b/flight/Flight.php
index 39fe83e..25d650a 100644
--- a/flight/Flight.php
+++ b/flight/Flight.php
@@ -61,9 +61,18 @@ class Flight
 {
     /**
      * Framework engine.
+	 * 
+	 * @var Engine $engine
      */
     private static Engine $engine;
 
+	/**
+	 * Whether or not the app has been initialized
+	 *
+	 * @var boolean
+	 */
+	private static bool $initialized = false;
+
 	/**
 	 * Don't allow object instantiation
 	 * 
@@ -98,7 +107,7 @@ class Flight
      * @param  ?Closure(T $instance): void $callback Perform actions with the instance
      * @return void
      */
-    static function register($name, $class, $params = [], $callback = null)
+    public static function register($name, $class, $params = [], $callback = null)
     {
         static::__callStatic('register', func_get_args());
     }
@@ -125,14 +134,12 @@ class Flight
      */
     public static function app(): Engine
     {
-        static $initialized = false;
-
-        if (!$initialized) {
+        if (!self::$initialized) {
             require_once __DIR__ . '/autoload.php';
 
             self::setEngine(new Engine());
 
-            $initialized = true;
+            self::$initialized = true;
         }
 
         return self::$engine;
diff --git a/flight/core/Dispatcher.php b/flight/core/Dispatcher.php
index e31d3f9..853a8f7 100644
--- a/flight/core/Dispatcher.php
+++ b/flight/core/Dispatcher.php
@@ -43,7 +43,7 @@ class Dispatcher
      *
      * @return mixed|null Output of callback
      */
-    final public function run(string $name, array $params = [])
+    public function run(string $name, array $params = [])
     {
         $output = '';
 
@@ -70,7 +70,7 @@ class Dispatcher
      * @param string   $name     Event name
      * @param callable $callback Callback function
      */
-    final public function set(string $name, callable $callback): void
+    public function set(string $name, callable $callback): void
     {
         $this->events[$name] = $callback;
     }
@@ -82,7 +82,7 @@ class Dispatcher
      *
      * @return callable $callback Callback function
      */
-    final public function get(string $name): ?callable
+    public function get(string $name): ?callable
     {
         return $this->events[$name] ?? null;
     }
@@ -94,7 +94,7 @@ class Dispatcher
      *
      * @return bool Event status
      */
-    final public function has(string $name): bool
+    public function has(string $name): bool
     {
         return isset($this->events[$name]);
     }
@@ -105,7 +105,7 @@ class Dispatcher
      *
      * @param string|null $name Event name
      */
-    final public function clear(?string $name = null): void
+    public function clear(?string $name = null): void
     {
         if (null !== $name) {
             unset($this->events[$name]);
@@ -123,7 +123,7 @@ class Dispatcher
      * @param string   $type     Filter type
      * @param callable $callback Callback function
      */
-    final public function hook(string $name, string $type, callable $callback): void
+    public function hook(string $name, string $type, callable $callback): void
     {
         $this->filters[$name][$type][] = $callback;
     }
@@ -137,7 +137,7 @@ class Dispatcher
      *
      * @throws Exception
      */
-    final public function filter(array $filters, array &$params, &$output): void
+    public function filter(array $filters, array &$params, &$output): void
     {
         $args = [&$params, &$output];
         foreach ($filters as $callback) {
@@ -204,7 +204,7 @@ class Dispatcher
     /**
      * Resets the object to the initial state.
      */
-    final public function reset(): void
+    public function reset(): void
     {
         $this->events = [];
         $this->filters = [];
diff --git a/flight/net/Request.php b/flight/net/Request.php
index 207df19..0f2cef9 100644
--- a/flight/net/Request.php
+++ b/flight/net/Request.php
@@ -37,7 +37,7 @@ use flight\util\Collection;
  *   - **accept** - HTTP accept parameters
  *   - **proxy_ip** - Proxy IP address of the client
  */
-final class Request
+class Request
 {
     /**
      * @var string URL being requested
diff --git a/flight/net/Route.php b/flight/net/Route.php
index 78b69a1..0ff17fa 100644
--- a/flight/net/Route.php
+++ b/flight/net/Route.php
@@ -15,7 +15,7 @@ namespace flight\net;
  * an assigned callback function. The Router tries to match the
  * requested URL against a series of URL patterns.
  */
-final class Route
+class Route
 {
     /**
      * @var string URL pattern
diff --git a/flight/util/Collection.php b/flight/util/Collection.php
index 39c03bc..f47b43e 100644
--- a/flight/util/Collection.php
+++ b/flight/util/Collection.php
@@ -21,7 +21,7 @@ use JsonSerializable;
  * @implements ArrayAccess<string, mixed>
  * @implements Iterator<string, mixed>
  */
-final class Collection implements ArrayAccess, Iterator, Countable, JsonSerializable
+class Collection implements ArrayAccess, Iterator, Countable, JsonSerializable
 {
     /**
      * Collection data.
diff --git a/tests/EngineTest.php b/tests/EngineTest.php
index 62fbf70..0a13fcb 100644
--- a/tests/EngineTest.php
+++ b/tests/EngineTest.php
@@ -227,7 +227,7 @@ class EngineTest extends PHPUnit\Framework\TestCase
 	public function testEtagSimple() {
 		$engine = new Engine();
 		$engine->etag('etag');
-		$this->assertEquals('etag', $engine->response()->headers()['ETag']);
+		$this->assertEquals('"etag"', $engine->response()->headers()['ETag']);
 	}
 
 	public function testEtagWithHttpIfNoneMatch() {
@@ -241,7 +241,7 @@ class EngineTest extends PHPUnit\Framework\TestCase
 		};
 		$_SERVER['HTTP_IF_NONE_MATCH'] = 'etag';
 		$engine->etag('etag');
-		$this->assertEquals('etag', $engine->response()->headers()['ETag']);
+		$this->assertEquals('"etag"', $engine->response()->headers()['ETag']);
 		$this->assertEquals(304, $engine->response()->status());
 	}